DE1537011A1 - Time division multiplex communication system - Google Patents

Description

Western Electric Company Incorporated R.A. Kaenel 30

New York, N.Y. 10007 U.S.A.

Time division multiplex message transmission system.

The invention relates to signal transmission systems.

A number of telephone systems have been known in recent years become, where the system costs are reflected by a summary from officially distant participants to groups and their Connection with a main office via one opposite the number of Participants can reduce the number of connecting lines. When connecting participants there are currently two uses basic possibilities, namely the space division switching method and time division switching. In the former case, each connection in the system between a calling and a called subscriber station or between a calling subscriber station and an inter-exchange line a unique Path defined by a number of switching elements will. The confidentiality of the conversations is ensured by their spatial Separation ensured. In the second case, a common transmission trunk is used for a number of connections, which has an outgoing and an incoming path to signal " samples one after the other in opposite directions during

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to transmit certain time intervals in repetitive frames.

The temporal separation points to the spatial separation The advantage that the transmission devices on a single transmission trunk which can be used simultaneously using inexpensive gate circuits. the required in the remote selector star switch (concentrator) However, means for transmitting voice and control information over the common bus are generally more complex. In addition, the blocking of possible connections between subscriber stations in time division multiplex systems is a special one Problem posed by the expansion of such systems, including several main offices, to which several offices were distant Selector star switches are connected, is made even more difficult. This problem can be traced back to the US Pat. No. 3,223,784 (Dec. 1965), in which each participant provides their own Has coding and decoding facilities. The increased effort per subscriber station, however, sets the obvious in the other case the economic advantages of such a system let reach. It also requires the use of delta modulation When coding, an elaborate time control process, which is still carried out by the sequences used in the known system. tial scanning of the subscriber sites is made more difficult.

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The problems explained are solved according to the invention in that signal samples from more than two subscriber stations are simultaneously on the outgoing path of the common bus, and that signal samples from the incoming path the common bus can be transmitted to more than two subscriber stations at the same time.

The signal sampling values are assigned in each subscriber station Facilities are coded and simultaneously transmitted to discrete locations of a register in the outgoing path of the common bus, and the encoded signal samples are simultaneously obtained from a register in the incoming common bus path transmitted to the decoder, which is assigned to a selected number of subscriber stations.

In its further development, the invention recommends that a register stores a plurality of signal samples received one after the other from a respective subscriber station and that the signal samples simultaneously to corresponding discrete locations in the register of the outgoing route.

An advantageous development of the invention provides that an activity register only the transmission of selected ones, received simultaneously by the subscriber stations in the register of the outgoing route

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Allows signal samples over the common bus. A buffer register in the outgoing path then gives the from the register in the " going path successively received samples only in the presence of gate signals from the activity register.

The invention is explained in detail below with reference to the drawings described. Show it:

Fig. 1 is the block diagram of a telephone system with a main « amt, several remote offices connected to the main office Selector star switches and with a large number of subscriber stations connected to each of the selector star switches or trunk lines to other telephone exchanges;

FIGS. 2A, 2B and 2C in the arrangement according to FIG. 6 essentially in the form of a block diagram the special facilities in each remote selector switch an embodiment of the invention;

FIG. 3 shows a schematic representation of a selector star switch of the exemplary embodiment according to the invention according to FIG. 2A facility used;

Fig. 4 is a block diagram of the main office for operating a the facilities provided for remote dialing switches;

Fig. 5 is a timing diagram of an office cycle for the control of a

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remote selector switch.

Structure of the plant

The telephone system according to Fig. 1 contains the officially remote en selector switch 101, 102 and 103 and the inter-exchange trunk line facility 104, each of which via corresponding transmission trunk lines 105 to 108 with the common control equipment in main office 100 are connected. The dialing star switches (concentrators) that are remote from the office are so named because there are a large number of individual ones Subscriber sites that are concentrated in the same area to this are turned on. All connections between star selector switches and within a star selector switch as well as connections between a selector star switch and a third-party exchange are in the main office 100 via the corresponding bus or bus lines 105-108 switched through.

The main office 100 assigns a specific one to a calling subscriber station Time slot in a cycle of time slots in which time information is provided by the calling and called subscriber via the appropriate manifold or manifolds 105-108. Other telephone connections are based on similar Way certain time slots are assigned in the cycle of time slots, so that the different channels are on a time basis

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are shared by the telephone connections, which in turn are temporal are separated from each other. In this way, considerable line savings can be achieved.

In the case of the system described in the above-mentioned USA patent a time slot mapping is used to overcome the blocking problem that occurs when there is no shared free time slot can be determined. It can therefore from the main office 100 to a subscriber station connected to the selector star switch 101 when the request is made a connection to a subscriber connected to the selector star switch 103 provide a first time slot and the called Subscriber station can be assigned a second time slot. The information from the calling party is then used for transmission to the called subscriber station in the main office 100 converted from the first to the second time slot, and vice versa.

The special equipments that are used in the main office 100 to carry out everything in the establishment of a voice connection in the plant according to Fig. 1 required functions and for performing the time slot conversion are shown in Fig. 4 and are described in detail in the aforementioned United States patent. As these control equipments are not part of the present invention, they are only described below with regard to modifications of the components and their connections, to adapt the main office with the equipment of the voting star

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switches according to the features of the invention are required, described. Suffice it to say here that from a selector switch Information received at Central Office 100 in a suitable form for use in the equipment of the aforementioned United States patent are present, and that in a corresponding manner in the selector star switch from the main office 100 received information is the same Have the same shape as in the aforementioned USA patent.

To establish a connection between two subscribers, an operating request is first made with the help of a continuous Scanning found what components are used in the office remote selector star switches, which will later be used in conjunction with the invention Features are described. The main office 100 has the marker 60 (FIG. 4) for identifying service requirements intended.

In the case of the system according to the USA patent mentioned above, a transfers particular control path the identity of subscriber lines requesting service, from the star selector switch to marker 60, In In the present system, these subscriber line identities are transmitted via the outgoing or send path 105-1 of the common bus 105 are transmitted in repetitive frames during a certain monitoring interval. The only deviation from that Plant according to the aforementioned USA patent in the main office concerns

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a simple timing operation that does the routing of the monitoring part of each incoming information frame from transmission path 105-1 to marker 60 is enabled. In a corresponding way is the output signal of the subscriber line number memory 20, which in the system according to the said USA patent on the Control path is given to the remote selector star switch, in. present case via the incoming or receiving path 105-2 the common bus 105 transferred. The subscriber line numbers are given here to receive route 105-2 take the supervisory part of every outgoing information frame.

Upon receiving an indication from the star switch 101 that a Subscriber station is in the unhooked state, causes the Markers 60 the subscriber line number memory 20 to determine whether the name of the scanned subscriber station there is recorded, indicating that it is busy. If the subscriber station was previously hung up, the Marker 60 to a free time slot, and the designation of the subscriber station is in the subscriber line number memory 20 in the assigned time slot. The subscriber line number memory 20 is therefore with reference to all active subscriber stations of the system and with regard to the time slots assigned to them up to date,

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The connection setup memory 90 causes the register to be occupied 80 before receiving the digits identifying the called subscriber. When register 80 is assigned, a signal to the sound system 70, which then sends an encoded sound via the gates 71 and the receive path 105-2 of the common bus to the selector star switch 101 there. This tone prompts the calling party to dial the desired number. The dialing pulses are transmitted via the transmission path 105-1 of the bus 105.

The monitoring circuit 50 determines all signals transmitted to the main office via the transmission path 105-1 and distinguishes between them these signals and the voice signals also given over the transmission path. When determining the digits identifying the called subscriber station, the monitoring circuit 50 provides this information to the previously occupied register 80. As soon as the busy checking facility is available after registration, the status will be of the called subscriber is checked and, if it is free, transmits the register 80 the stored digits to the marker 60. The marker then causes the allocation of a free time slot to the called subscriber station taking into account the subscriber line number memory 20.

If both the calling and the called subscriber stand corresponding time slots are assigned, the marker 60 outputs them

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Allocations to the pulse shift memory 45, the memory 45 counts the number of time slots. Between that of the called subscriber station and the time slot assigned to the calling subscriber station and stores an indication of this difference. The saved Information is read during each office cycle and causes gates to be actuated in the pulse shifter In this way, the signals received in the pulse shifting device 40 from a subscriber station via the corresponding transmission path Information delayed until the occurrence of the time slot assigned to the other subscriber station of the connection and then from the pulse shifter 40 transferred to the specified subscriber station.

Time control

To make it easier to understand the individual operations in the system, the special time control and, for this purpose, a certain time sequence according to FIG. 5 can be considered.

A key feature of any time division multiplex system is that the Sampling must be done at a frequency that is at least twice as large as the highest signal frequency, in order to achieve the correct reconstruction of the signal at the receiving point. In the case of voice transmission, the sampling frequency must therefore be at least 8 KHz be. The use of delta modulation leads to another

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Restriction in such systems, as it is about six times the value of the minimum sampling frequency is required for proper recovery of the encoded signal sample. The ones in the distant office Information stored in the selector star switch can be assigned a frequency of 0.5 MHz, or with a shift of a position through the various district wall registers at an interval of two microseconds. This bit shift frequency represents a further feature for information processing in the present system.

It is assumed that 100 subscribers are connected to the selector star switch 101, and that 20 time _{slots S 1} , S- .. .S _2n are available and are sufficient for the traffic requirements. The 20 time slots appear in a cycle F, which is referred to as a frame. As indicated below, the samples taken simultaneously from each subscriber station must be transmitted in serial form during each frame. In order to be able to transmit 100 sampled values with the bit shift frequency of 0.5 MHz, a frame of 200 microseconds would be required. The resulting sampling frequency would then be only 5 KHz, that is, one tenth of the value required on the basis of the first criterion. In order to meet the required sampling frequency of 50 KHz with this arrangement, a frame of 20 microseconds and a bit shift frequency of 5 MHz would be necessary. Such a bit shift

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frequency would be difficult to achieve with the district wall facilities available today.

From the above one could conclude that a. Selector star switch with 100 subscriber stations, which are served by 20 time slots, cannot be operated in such a way that it meets both conditions enough. The extensive adaptability of district wall facilities but according to the invention enables such an arrangement that both conditions can easily be met. Instead of that each subscriber station is scanned only once per frame., a number of samples can be obtained and simultaneously divided into separate Input register. In this solution, the bit shift frequency remains constant while the sampling frequency is increased. In the example explained above, where a bit frequency of 50 KHz and a frame of 200 microseconds for 100 subscriber stations leads to a sampling frequency of 5 KHz, ten simultaneous samplings per subscriber would represent the sampling frequency increase to the useful value of 50 KHz.

Another possibility would be to place the 100 participants in certain To divide groups and to assign an appropriate number of the 20 time slots to each group. The sampling frequency remains constant, while the bit shift frequency is increased. With the one above explained example with a sampling frequency of 50 KHz and the

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The resulting frame of 20 microseconds would in turn subdivide the 100 subscriber stations into ten specific groups Bit shift frequency to a useful value of 500 KHz humiliate.

A combination of these two possibilities leads to an optimal one Arrangement. In the present exemplary embodiment, the 100 subscriber stations are accordingly in five groups of 20 subscriber stations each divided. Two samples per frame are taken from each subscriber station and in two identical sections of the data input register saved. This results in a frame of 42 microseconds, with 2 microseconds for sampling and 40 microseconds Microseconds are available for transmission. At this Arrangement, a useful value of 48 KHz for the sampling frequency and 500 KHz for the bit shift frequency is achieved.

In addition to the information samples, monitoring signals, indicate the changes in the state of the subscriber lines, and frame signals, which indicate the persistence of the exact, im Ensure the time control of the frame intervals established by the main office in the remote dialing star switch before the transmission inserted into each frame of information samples to the central office. This can be done easily without changing the basic frame length achieve by just setting the bit shift frequency for the

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Transmission between the star switch and the main office is increased beyond the value required for scanning and processing is required in the selector star switch. The bit shift frequency is then used for processing at its destination returned original value.

For example, assume that seven bits are used for identification each of the 100 subscriber stations is required, and a bit for identification, how a subscriber station has changed its monitoring status and that seven bits are required for framing will. These fifteen bits must then be among those available in each frame forty bits of information are added, d. i.e., two bits in each of the twenty time slots, and the total of 55 bits must be available on the outgoing path of the common bus Shift interval of 40 microseconds can be given. To do this, the bit shift frequency must be increased to 1.375 MHz. This value can easily be achieved with the facilities available.

The timing diagram according to FIG. 5 is based on the example explained, in which a selector star switch with 100 subscriber positions through twenty Timeslots is served, and the subscriber stations are divided into five groups of twenty subscriber stations each. Put in the diagram t the bit shift frequency of 500 KHz, t the sampling interval of 2 microseconds in which two information samples each

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Subscriber line removed and in separate data input registers stored, and t "represents the transmission interval, in which the information stored in each data input register of each group with twenty subscriber positions with the bit 'shift frequency t be pushed out, which takes up the rest of the frame with 42 microseconds. The others indicated in FIG Time intervals are described below in connection with the operations described in the system.

The various gates and other components of the plant are through precisely synchronized signal pulses are controlled so that the information between the calling and called subscriber can be transferred via the Main office 100 can be transferred in the assigned time slots. The timing within a frame is controlled by a common Pulse source produced in the main office 100, which is designated in Fig. 4 with main clock 91. This pulse source operates all selector star switches and all control equipment in the office to maintain synchronism and perform all timing operations.

The slave clock 240 (FIG. 2B) provides the signals required for the Operation of all components in the star selector switch 101 are required, and is held in synchronism with the central office by frame circuit 241. With the ability to have multiple frame bits in each

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Sending and receiving frames is keeping the correct ones Framework order in the selector star switch easy to implement.

With the delta modulation used here, the same binary digit is transmitted one after the other as often as possible, around the rise time of the signal to be transmitted with the highest frequency. Similarly, it becomes the opposite binary digit sequentially as many times as possible to keep the fall time of the from to represent an active subscriber line to be transmitted signal with the highest frequency. Taking into account that the highest Signal frequency is 4 KHz, three samples of the same binary digit are consecutively at a sampling frequency of 48 KHz at most occur one after the other. A unique frame signal can therefore consist of four or more consecutive identical binary digits exist without overlapping with the transmitted coded speech signals.

Since there is always a binary one to reproduce the attached state If zero is transmitted, the binary one is used for framing. Five consecutive binary one values can accordingly can be selected as the frame code. Since this group also represents the binary number 16, this number is not used for a subscriber line assignment used. When the frame circuit 241 has five consecutive ones from the receive path of the bus

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Αψ.

receives, it causes the clock 240 to output the signal t. It also puts the frame code in the transfer register for transmission via the transmission path in the next frame. To this Thus, during each frame interval, the frame synchronization becomes carried out.

Before a detailed explanation of the operation of the remote selector switch, it is useful to use the special Consider elements that make up those shown in Figures 2A-2C Main components exist. As indicated, in this example there are five groups with twenty subscriber stations each on the selector star switch 101 switched on, and two samples are taken from each subscriber station in each frame.

Subscriber circuit

The line circuit of the subscriber station 201-1 (Fig. 2A) _- which is equal for each of the 100, is switched to the line concentrator 101 subscriber stations, the conventional hybrid circuit 202 to which the reaction of the two-wire subscriber line to the four-wire bus 105 performs. The outgoing voice and monitoring signals are stored at the output of hybrid circuit 202, so that when a timing signal is received in a coding circuit, expediently a delta modulator 205,

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a signal sample encoded and a data input register 210 via a short shift register to be considered in the following 206 is supplied.

The coding circuit 2 05 converts the speech and monitoring signals in coded output pulses using a known and described with some details in the above-mentioned US patent delta modulation method. In this In this case, the delta modulator delivers a specific output signal, for example a sequence of zero values, which a subscriber station designate in the hanging position. If the subscriber station has hung up but is not transmitting any information, the delta modulator delivers a second specific output signal, for example alternating one and zero values. When the subscriber station has finally hung up and is transmitting information, the delta modulator delivers Combined output signals that follow the amplitude of the input signal. For example, a sequence of one values can be one continuous increasing amplitude and a sequence of zero values denote continuously decreasing amplitude. This particular coding is necessary for a correct display in the main office of the plant required according to the above-mentioned USA patent.

Coded information that is received by the main office 100 via the reception path of the common bus 105 and for the

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Subscriber place 201-1 are determined first in the data output register 215 stored, from where it is subsequently forwarded are, for example via the AND gate 216 and the short shift register 217 to the delta demodulator 207. When receiving of the corresponding timing signal, the demodulator 207 converts the coded signals into speech signals which are amplified and transmitted via hybrid circuit 202 to subscriber station 201-1 will.

District wall expansion register

The various registers used in selector star switch 101 are, with the exception of the transfer registers 250 and 260 (FIGS. 2B and 2C), advantageously of a type in which, in a known manner, a district wall expansion is used. The registers 250 and 260 are expediently shift registers of a known type. Understanding the reason additional structure and mode of operation of district wall expansion registers. for understanding the mode of operation of the star selector switch 1.01 useful. For this purpose, a part of such a register is shown in FIG. It includes an elongated Magnet wire 300, which is used to facilitate understanding of the relationship between the various windings on the wire in seven specific views is shown. In Fig. 3A is a thin one electrical "conductor 3 01 at distant points with the

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Wire 300 coupled. The conductor 300 is between a driver and Earth switched. The driver can use the local clock 240 (Fig. 2B). As shown in Fig. 3B, input signals are which are received with reference to the data input register 210 from the corresponding subscriber stations, near the coupling points of the lead conductor 301 coupled to the magnet wire 300. According to Fig. 3C is also a read conductor 302, between a consumer and ground is coupled to magnet wire 300.

The magnet wire 300 itself is helical around an elongated non-magnetic Core wrapped. As shown in Fig. 3D, two propagation conductors are arranged with respect to wire 300 so that these alternating pulses applied by the source 303 reverse a magnetic district of a stable length step by step along the wire 300. Such propagation conductors and their arrangement with reference to the core to achieve such a handoff are known.

The magnet wire for district wall expansion registers contains in typically a ferromagnetic material with essentially rectangular, self-recurring hysteresis characteristics. Such a material shows a steady state of flow, the reversal district is called when a magnetic field is greater than a predetermined coercive force using one of the input lines to a section of wire sufficient length is created. A reversal district is in

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3 represented by the arrow pointing to the left in wire 300. The normal condition of the wire 300 is indicated by arrows pointing to the right in FIG. 3. Once a reversal district is established is, it can be passed along the magnet wire 300 by a polyphase propagation field of relatively small amplitude generated by pulses applied to the propagation conductors. The propagation along the wire 300 occurs in the direction of the read conductor 302, which then for each arriving at him District wall generates an output pulse.

The conductor 301 is pulsed periodically to target the desired areas in the wire 300 for subsequent propagation produce. The amplitude of this drive pulse is chosen so that the Impulse alone is not able to create a reversal area in the magnet wire 300 to generate. However, if an input signal is received from one or more input lines at a time when a driving pulse is applied to the conductor 301, a stable reversal region becomes in the corresponding sections of the magnet wire 300 generated. In this way information can be stored in the shift register with the magnet wire 3 00 by the simultaneous occurrence of input signals on the drive conductor 301 and one or more of the input lines. This stored information can then be sent by applying a sequence of signals the propagation ladder moved along the wire 300 and then

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be pushed out via the reading ladder 301.

In Figures 2A-2C, the magnet wire is each district wall expansion register Shown as a rectangular block divided into sections to indicate areas in which districts are formed can be. The arrows directed to each section correspond to the input lines in Fig. 3. Similarly, this corresponds to input signal applied to one end of the register block to the propagation ladder, and the output line from the opposite end of the register block corresponds to read conductor 302 in FIG. 3. The drive conductor 301 is not shown in FIGS. 2A-2C, although it is of course necessary for the storage of information in each register block is.

Data input and output registers

The data input register 210 in FIG. 2A receives information samples simultaneously from each of the twenty subscriber stations in group 1 during each frame interval by applying the output signal of the corresponding delta modulator, for example 205, to certain associated areas of the register 210 Clock signal t _o at the output of register 206, which in turn receives the output signal of delta modulator 205, a pair of coded signal samples from the subscriber

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put 2Ql in corresponding discrete areas of register 210 saved. Since a De It a modulator supplies a binary output signal, it is assumed that a 1 represents a reversal district in the data input register while a 0 forms the magnet wire in its normal state in the specific area to which the input signal is created.

The data input register 210 is advantageous in this exemplary embodiment of the invention is divided into specific sections so that it can be applied to a plurality of data samples obtained from each of the corresponding Delta modulators have been obtained without increasing the propagation time. A clock signal is used for this purpose t "applied to all delta modulators at the same time, in order to first Signal samples in the short shift register, e.g. 206, respectively. A propagation signal t_ applied thereafter moves the stored signal samples by the distance of a district along register 206. The clock signal t then becomes simultaneous again is applied to all of the delta modulators to introduce second signal samples into the register 206 in those areas previously defined by the first signal samples have been assigned. This alternating storing and expanding is repeated until the desired number of signal samples from each subscriber station are. In Figure 2A are two samples from each of the twenty delta modulators in group 1 in the corresponding short sliding

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registers, for example 206, and when creating a Clock pulse t, the content is given simultaneously to the corresponding positions in the two sections of the data input register 210, so that a total of forty samples are stored there.

After the storage operation is completed, the stored information simultaneously by applying a sequence of clock signals t during the propagation interval t "through the two sections of the Register 210 spread out. The clock signals are advantageously applied simultaneously to both sections of the register with a frequency, such that the register is cleared before a new sequence of signal samples has to be entered. At a bit shift frequency t / of 0.5 MHz become two signal samples received in two microseconds from each of the twenty subscriber stations and stored in the data input register 210, so that a Interval of 40 microseconds is available in which the twenty samples stored in each section from the register 210 must be pushed out. In this case, the propagation with a frequency of 0.5 MHz leads to an overall frame of 42 microseconds (Fig. 5). It should be noted, however, that the number of signal samples and the number of those connected to register 210 Subscriber positions may vary depending on the requirements of the facility. In this case the sampling frequency will be and also change the propagation frequency accordingly.

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The data input register can be connected directly to one end of the transmission path of the common bus 105. In order to explain however, the register is in Pig. 2A shown as a separate register, which is connected to the transmission path via intermediate buffer registers 255 (Fig. 2B) is connected, in this case a selection of signal samples from a maximum of four of the twenty subscriber stations in group 1 for transfer to the main office. The selection process will be discussed later in conjunction with the Activity Register 220 described. It should be noted, however, that at any point or points along a district wall shift register, the propagation initiated, information can be entered and stored data can be read.

The operation of the data output register 215 corresponds to that of the Data input register 210. Data samples are added to the input transfer register 260, which completes the reception path of the common bus 105, and in parallel to buffer registers 265, which in turn registers its output signals via lines 268 to the first district in each section of the data output 215 on receipt of a concurrent signal from activity register 220 to be considered later. The saved Samples are propagated through register 215 until they occupy an area to which the subscriber is assigned to which they are to be applied. Coincidence gates, for example that

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AND gate 216, receive a stored sample from one District in each section of register 215 and provide output signals upon simultaneous receipt of a signal from a corresponding one District in the. Activity register 220 still to be considered. As a result, all of them are stored in data output register 215 Information is output in parallel form and subsequently applied to the corresponding delta demodulators, for example 207.

Subscriber line scanner

Subscriber line scanner 230 in FIG. 2A, which includes group 1 with Serves twenty subscriber stations, has two district wall registers 231 and 232. The first-mentioned register is called the current state register and the second-mentioned register is called the review register. The current state register 231, as its name suggests, stores the current state of each of the twenty subscriber stations in group 1. On command, the contents of the current status register 231 shifted in series form into the review register 232. In a subsequent operating cycle, a new information entered into register 231 for the current state of each subscriber station, and upon receipt of the next shift command the content of both registers is applied in series to the exclusive OR circuit 233, which only supplies an output signal, if there is a mismatch between their two input signals

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is available. Such a mismatch indicates a change the monitoring status of the respective subscriber station, the corresponds to the content of the register currently being viewed.

According to the particular timing used in this embodiment of the invention, the current state becomes any Subscriber station of group 1 once every 100 frames or at intervals of 4.2 milliseconds by applying a pulse t to the AND gate 203 at the output of hybrid circuit 202 during sampling interval t. observed that once for every 100 frames occurs with a duration of 42 microseconds. The participant positions of the other four groups are also in the interval t. scanned.

Advantageously, according to the invention, the output signal from the scanner 230 is used directly to store and transmit the corresponding subscriber number to the main office via the transmission path of the common bus line 105. The flip-flop 240 is set by a scan shift pulse t applied once every five frame interval, and the set output gate of the flip-flop give signals t. via the AND gate 241 further ₃ which advance the two scanner registers 231 and 232. A state change signal supplied by the exclusive OR circuit 233 resets the flip-flop 240, thus stopping the Abatser propagation

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and causes the subscriber line number generator 245 to do its current content via the corresponding AND gate 251 and the OR gate 252 into a particular one for the subscriber line scan information to shift the reserved portion of the transfer register 250. In this way, the scanner 230 shifts data until a change of state has been detected or until the interval is ended with 100 frames. After a change of state has been determined, the scanner 23 0 stops at the corresponding line number, the generator 245 outputs and the arrival again of the next scan shift pulse t ,. expected.

The output signal from the OR gate 233 is also applied to the AND gate 242, which is a change of state information for the corresponding subscriber line to the generator 245 is there. So if a service request arises at a subscriber station., There the AND gate 242 an output signal to the generator 245, if the corresponding subscriber number appears in this. If on the other hand the subscriber has just broken a connection, the AND gate 242 does not provide an output signal. This indication of the monitoring status the participant is sent to the transfer register by the generator together with the corresponding participant number 250 given. In this way, the central office and activity register 220 recognize that in this embodiment receives the subscriber number from the main office, immediately if one

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Operation request or disconnection is displayed. In the present Case identified at 100, connected to selector star switch 101 Participants put a number with seven digits a participant place, whose monitoring status has changed, and an additional number indicates the type of change.

It should be noted that the output of the AND gate 241, which passes the information through the scanner 230, also the subscriber line number generator 245 acted upon in such a way that the correct subscriber number is immediately available to the subscriber station to identify the monitoring status of which is indicated by the output signal of the exclusive OR circuit 233 has changed. Forwarding of information through the sampler 230 continues until either an output signal is provided by the exclusive-OR circuit 233 or a sampling signal t is provided. is applied to the reset input of flip-flop 240. The last " called signal is also sent to the subscriber line number generator 245 is applied to reset its count to zero.

In summary, there are five groups of subscribers in the selector star switch 101 with twenty subscribers each Group of each scanner 230 twenty monitor states. These states are sequentially once every 100 frames with a duration of 42 microseconds observed. A change of state of a part

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The recipient position is therefore in a maximum interval of 4.2 milliseconds and reported to the chief office via the transmission route of the bus line 105.

Activity register

Activity register 220 in Figure 2A contains two district wall registers

221 and 222, in which data circulating that the monitoring state or indicate the activity status of each subscriber station connected to the selector star switch. Register 222 provides output signals in parallel to the AND gate. 216 in conjunction with the output signals from the data output register 215. If a certain subscriber station is active, the data output register 215 is sent to this Subscriber station-directed information about the corresponding AND gates 216 upon the appearance of the signal t and an activity signal from the corresponding region or data storage area in the register

222 transferred.

The activity status of each of the twenty subscriber stations in group 1 is stored in activity register 220 and with each Change of the monitoring status by the cooperation of the register 221 with the comparison circuit 223 to the newest status brought. So it will be every time the identification a subscriber line in the input transfer register 260 over

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the receiving path of the common bus 105 is received, the identifying digits in parallel via the AND gates 266 and cable 267 are transmitted each time the signal t occurs and stored in address register 224.

The address register 224 is set up in such a way that, after the digits required to identify a particular subscriber station have been stored, the corresponding address is given to the comparison circuit 223. At the same time, subscriber line number generator 225 cycles through the numbers that identify each of the twenty subscriber stations in group 1 under control of signals coming from AND gate 227. The signals from AND gate 227 are provided during the propagation interval t _Q and correspond to timing signals t of 500 KHz. All subscriber numbers are thus generated once in each frame interval and sent to the comparison circuit 223, which then supplies an output signal if the number received from the generator 225 matches the number received from the register 224. This output signal is given to a special area in register 221. The activity states of the twenty subscriber stations of group 1 run in registers 221 and 222 at the same frequency as the subscriber numbers in generator 225. So there is a synchronization, such that the area of register 221, which the output signal of the Comparison '

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Circuit 223 receives which corresponds to the particular subscriber number, which is currently being compared in register 223.

When the comparison is carried out, an indication of the activity is displayed in the Register 221 is stored, which corresponds to the subscriber position which has provided an indication of a change in the monitoring state from the passive to the active state. In a similar way there the comparison register 223, if an active subscriber station is currently has returned to the passive state, a signal to the register 221, which provides the stored activity signal for these participants clears.

The output signal of the register 221, which, as indicated, the activity status of all subscriber stations connected to the selector star switch is sequentially sent to register 222 for the following Control of the output data applied to the subscribers are given and also via line 226 to both buffer registers 255 and 265, which transmit data to and from the common bus 105. As stated above, the mode of operation of the selector switch to be adapted to the main office, the time division multiplex using a certain number is operated by time slots in each frame interval for the transmission of information between active subscriber stations. Even though that is, data in each frame from all to the selector star switch 101

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connected subscriber parts are received, it is only necessary and of course useful to transfer data from active subscriber stations to the main office. An analysis of the volume of traffic in the special selector star switch determines the number of time slots that are connected to the selector star switch Participant positions should be available. In the present pail, in which, for example, twenty subscriber locations through the in Pig. 2A Group 1 equipment shown are operated, four data time slots may be sufficient for usable operation. then could five such groups of twenty subscriber stations data in parallel to the transfer register 250 {Fig. 2B) deliver the Transmission path of the common bus 105 completes to the available to fill twenty time slots.

If four time slots, namely the indicated time slots 17-20, the assigned to a special group of twenty subscriber stations according to FIG. 2A, the activity register 220 contains activity information in four of the twenty districts of each of registers 221 and 222. When an indication of activity reaches the output of register 221, will them to the propagation inputs of the duplicate sections of the buffer register 255 (Pig. 2B) and the special data sections that are currently being used by the corresponding active subscriber station are available via the data input register 210 are in this moved by one position. During the interval between the

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If activity signals occur at the output of the register 221, no information is propagated via the buffer register 255, so that during this interval the data supplied by the input register 210 are effectively deleted. At the end of each frame, the two sections of the buffer register 255 each contain four coded information samples which correspond to the four time slots available for group 1. These binary-coded digits or bits are placed at the beginning of each frame at t _o in corresponding positions of the transmission

Ci

registers 250 given, specifically for transmission to the main office via the transmission line of the bus 105 with an increased bit shift frequency, to clear the register at the end of the frame.

The output signal from register 221 is also given to the two sections of buffer register 265 (FIG. 2C), which receives _{information in parallel from the reception path of common bus 105 at time t o.} Again, this information can

2t

mation can only be transferred to the data output register 215 if an activity signal has been received from register 221 and thus ensured is that the correct area in the data output register 215, which corresponds to an active subscriber station, the specific, im The data portion appearing at the moment in the buffer register 265 is received from the common bus 105.

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Editing a connection

How the system works when establishing a connection between a calling and a called subscriber station of the same selector star switch shall now be made with particular reference on the selector star switch devices according to Pig. 2A-2C and the timing diagram in Fig. 4 will be described. The participant in the Subscriber station 201-1 wants to establish a connection to subscriber station 210-1 and directs the operation of the system by picking up the handset a. The scanner connected to the hybrid circuit 202 in the subscriber circuit of the calling subscriber place 201-1 reports the off-hook status as a voltage drop in the subscriber circuit appears to a corresponding data storage area in register 231 during the sampling interval t ,, that once in each 100 frames occurs. As indicated above, each subscriber station connected to this selector switch will be switched during this sampling interval t. observed.

After the scanner 230 has stored the display in the register 231, it shifts the stored information when the scanning shift signal t ^, which is used to set the flip-flop 240, is applied to the register 232. Thereafter, each of the pulses X applied to the AND gate 241 shifts ^ the information stored in registers 231 and 232 by one position. This causes corresponding areas of each of registers 231 and 232 to have the stored

.'90982870976

Apply information to the exclusive OR circuit 233. A mismatch occurs when the content of the instantaneous state- and the review area of the registers 231 and 232 corresponding to the calling subscriber station are read from the registers 231 and 232 will. The exclusive OR circuit 233 then provides an output to reset the flip-flop 240. The same output signal causes the subscriber line number generator 245 to generate the number corresponding to the calling subscriber station in parallel via cable 246 to a discrete area of output transfer register 250 via AND gate 251 and the OR gate 252 of group 1 when the signal t .. It should be noted, however, that the mere transmission of the identity of the subscriber station is not sufficient to inform the main office with reference to the type of change in the monitoring status that has occurred. For this purpose, the AND gate 242 is provided in the scanner 230, that an additional bit always in the output register of the subscriber line number generator 245 begins when the respective subscriber station under consideration moves from the hooked to the unhooked State goes. In connection with this, it should be noted that a transition from the on-hook to the off-hook state requires an information bit in the corresponding area of the current state register 231 in the scanner 230. The output of register 231 is offset So together with an indication of a mismatch from the exclusive OR circuit 233, the AND gate 242 is in the position

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to provide an output signal indicating this particular change in state indicates. If, on the other hand, the change in status to be reported is a transition from the unhooked or active state to the hung up or passive state, a data bit is not in the current state register 231, but is found in the corresponding area of the review register 232. It is therefore an output signal for this special participant represent the exclusive-OR circuit 233 derived that in "connection with an input signal from register 231 energizes AND gate 242, and that in the subscriber line number generator 245 stored data bit indicates this change in the state of the participants. This monitoring » The data bit can precede the subscriber number whose monitoring status it indicates when it is transmitted to the main office or where it is handled appropriately by marker 60.

When the main office provides the special subscriber, the change of state shows, and has determined the type of change, the subscriber number and the monitoring bit are stored in the subscriber line number memory 20 returned on the receiving path of the common bus 105 to the selector star switch. If the watchdog bit that the activity register 220 has via the Input transfer register 260 reaching AND gate 266 and cable 267, a change from on-hook to off-hook upon initiation of the connection by the subscriber

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201-1 to subscriber 210-1, the comparison register 223 enter activity information in the area of register 221, which corresponds to subscriber station 201-1.

It will then be the number that the calling subscriber station 201-1, along with the indication of the change in state of the output transfer register 250 during the propagation interval and transmitted via the transmission path of the common bus line 105 to the marker 60 in the main office 100 (FIG. 4). Of the Receipt of this number initiates processes in the marker ^ 60 assign a specific time slot to the calling subscriber station and the designation of the calling subscriber station in the assigned Register the time slot in the subscriber line number memory 20, where it rotates for the duration of the connection. The marker 60 marks this time slot as occupied and transmits a dialing signal from the sound system 60 via the signaling and sound gates 71 and via the reception path of the common bus line 105 in the associated Timing. This information is given to the data output register 215 via the buffer register 265.

In addition, the subscriber line number memory 20 gives the Number of the calling subscriber station in the monitoring section of the transmission frame on the receiving path. This number will during a subsequent interval t "to the activity register

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given. The number of the calling subscriber station is compared with the group 1 numbers contained in the generator 225 during the Propagation section t "of the same frame compared, and if a match occurs, the activity signal is from the comparison store 223 is transferred to the register 221. In the activity register 220 the calling subscriber station is thus registered as active.

This activity indicator circulates in register 222, and when the next interval t occurs, two output UNd gates 216 feed samples of the coded dialing character from data output register 215 to short shift register 217. When the calling party hears the dial tone, he dials the number of the called party station 210-1. The changes in state on the subscriber line caused by the dialing process are encoded in the DeIta modulator 205 and stored in the short shift register 206 at a frequency of two samples per frame during the propagation interval. They are then stored in corresponding discrete areas of the two sections of the data input register 210 during the next data input interval X. During the following propagation interval t_, the stored information is passed via output lines 211 into the buffer register 255 in the respectively assigned time slots that are determined by

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the occurrence of the activity indicator at the output of the register 221 on line 226 during the same frame. Then the samples in the interval t are in parallel form led to the transfer register 250, from where it is processed with increased Frequency to be transmitted to the main office.

These dialing pulses are in the main office 100 in the monitoring circuit 50 received and processed in the manner described in detail in the aforementioned USA patent. After finished Storing the dialing digits that designate the called subscriber station becomes a busy check of the called subscriber station carried out. For this purpose, the dialing digits stored in the monitoring register 80 are assigned to markers 60 via τ carry where the designation of the called subscriber station with the information stored in the subscriber line number memory 20 mations is compared. If this comparison shows that the called Subscriber station is not stored there, the marker 60 assigns a time slot to the called subscriber and saves it the designation of the called subscriber station in the subscriber line number memory 20. Information about time slots is now available to the marker 60, that of the calling and the called Subscriber station are assigned. The marker then transmits this information to the pulse shift memory 45, which in turn the excitation of the pulse shifter 40 in successive frames

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prepared while the connection between the calling and called Participant position exists.

After assigning a free time slot to the called subscriber station gives the sound system 70 to this a call sign via the signaling and sound gates 71 and the reception path of the common Bus 105 in the assigned time slot. The tone system 70 gives the same character to the calling party in this assigned time slot, so that both participants hear the same character in the time slots assigned to them.

The monitoring circuit 50 now monitors the status of the called Participants ask in the time slot assigned to them, and if so the off-hook condition is detected, the various control circuits used in establishing the connection are included of the marker, the monitoring circuit 50 and the Register is put to sleep. The voice transmission over the existing connection is stored in the activity register 220 with the aid of the for the calling and called subscriber station Maintain activity indicator in such a way that every bit of information from the main office via the common collecting line 105 in the time slot assigned to the calling or called subscriber station is received from the output data register 215 with the aid of the activity information contained in register 220 of the corresponding

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Subscriber station is supplied.

The monitoring circuit 50 continues to monitor the connection. If the connection is made by the calling or called subscriber station is interrupted, the scanner 230 represents the change in the monitoring state of the subscriber station from the unhooked to the hung state and transmits the subscriber number and the type of transition to the main office in the manner described above in connection with hanging up the calling party. To After processing, the central office returns this information to the selector star switch 101, where it is received in the activity register 220. In this case, the comparison register 223 gives an opposite signal to the register 221 to the subscriber station present there 201-1 to clear the corresponding activity signal. This is the only process that takes place in the selector star switch when one of the Participant of the connection is required.

It should be noted that since the subscriber station and its current status are fully identified and removed from the selector star switch have been reported to the main office, complicated facilities for the separation of information and control signals and for Identification of certain control signals in the main office in the case of the invention Embodiment are not required. It should also be noted that if the called subscriber station is at the

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Establishment-the connection explained above is busy, the various Tax operations in the main office according to the one mentioned above USA patent specification meet the requirements of the present system. So if the called subscriber 210-1 is occupied by an earlier connection, a is the subscriber station in the activity register 210-1 corresponding activity signal must be present. This Status is not disturbed, as the busy status first occurs in the main office is detected. The sound system then gives a busy signal 20 to the calling subscriber 201-1 via the reception path of the common Bus 105 given in the assigned time slot in the manner described for dialing and callsigns, the determined Indicates the busy status of the called subscriber.

When disconnected by the called subscriber 201-1, the hybrid circuit 202 and the AND gate 203 transmits the status change signal to the scanner 230 during the next sampling interval t Transition from the unhooked to the hung state indicates to the main office. The marker 60 determines the subscriber station number and the transition indicator and takes appropriate steps to clear the time slot assignment for the subscriber station 201-1. The following is the number of the subscriber and the transition bit from the subscriber line number memory 20 via the

9.0982870976

Receiving path of the common bus line 105 to the selector star switch transfer. The comparison process is repeated and leads to the final deletion of the activity display in that of the subscriber station 201-1 corresponding area. All equipment used for this connection is then reset to the idle state.

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Claims (9)

PATENT CLAIMS 1. Signal transmission system with a variety of Subscriber stations and a common transmission bus, one outgoing and one incoming path for the sequential transmission of signal samples has frames repeating in opposite directions during certain time intervals, characterized in that signal samples from more than two subscriber stations (201-1 to 220-1) simultaneously are transmitted to the outgoing path (105-1), and that signal samples from the incoming path (105-2) be transmitted to more than two subscriber stations at the same time. 2. Signal transmission system according to claim 1, characterized characterized in that coded signal samples are assigned simultaneously from each subscriber station (201-1 to 220-1) Encoding device (205) to corresponding discrete locations of a register (210) in the outgoing path (105-1) of the common Transmission trunk (105) and that encoded signal samples are transmitted simultaneously from one Register (215) in the incoming path (105-2) of the common transmission trunk to the decoder (207) are transmitted, which is assigned to a selected number of subscriber stations. 9 0 9828/09 7 6 3. Signal transmission system according to claim 1, characterized characterized in that a register (206) stores a plurality of signal samples which are successively obtained from a corresponding subscriber station (201-1 to 220-1) have been received, and that the stored Signal samples simultaneously to corresponding discrete locations of a register (210) in the outgoing path (105-1) be transmitted. 4. Signal transmission system according to claim 1, characterized characterized in that an activity register ((220) only the transmission of selected, simultaneously from subscriber stations (201-1 to 220-1) in the register (210) of the outgoing path of received signal samples via the common transmission s manifold (105) allows. 5. Signal transmission system according to claim 4, characterized in that a buffer register (255) in the outgoing Path (105-1) of the common trunk (105) sequentially from the register (210) of the outgoing path continues received samples only in the presence of gate signals received from the activity register (220). 909828/0 976 6. Signal transmission system according to claim 5, characterized in that a scanner (230) detects the subscriber stations (201-1 to 220-1) which are currently requesting service, and a designation of a subscriber requesting service for the outgoing Wegfr (105 -1) of the common transmission trunk (105) 7. Signal transmission system according to claim 6, characterized in that the scanner (230) has a scanning register (231) to which the monitoring status of each subscriber station (201-1 to 220-1) is applied simultaneously, as well as a number generator (245) which provides a sequence of numbers for identifying each of the participants in a repetitive cycle delivers and the generated Number along with an indication of the type of service request when receiving a Indication for a service request leads from the scan register to the common bus (105). 8. Signal transmission system according to claim 7, characterized in that the activity register (220) has a Number generator (225) which contains a sequence of numbers to identify each of the subscriber stations (201-1 to 220-1) 903828/09 supplies in a repetitive cycle, as has a compare register (223) which contains the content of the Number generator with the names of Subscriber stations compares, and that the comparison register when a comparison is determined an outgoing Signal is applied to the register (221) connected to the buffer register (255) in order to detect an active subscriber part and identify the time interval in which signal samples from the active subscriber station via the common transmission trunk. 9. Signal transmission system according to claim 8, characterized gekennae that the activity register (220) records the contents of the register (215) in the incoming path at the same time to each of the subscriber stations (201-1 to 220-1) of an existing connection passes on. 903828/0976 -H9- Blank page